Capacitive and inductive sensors for diagnosing air-gap anomalies in synchronous generators

Caetano, Ricardo Elias; Chabu, Ivan Eduardo; Stolfi, Guido; Santos, Josemir Coelho; Junior, Shigueru Nagao; Gomes, Carlos Eduardo Marmorato; Paiva, Raul Dias; Nabeta, Sílvio Ikuyo; Micerino, Fabio Jose

doi:10.1109/iemdc.2015.7409126

Cited by 5 publications

(4 citation statements)

References 7 publications

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“…Besides, Bruzzese C. et al found that the amplitude of the second harmonic ripple in rotor current is proportional to the degree of the SAGE fault [7], and the first and third harmonic amplitudes of the electromotive force increased significantly under the SAGE fault [8]. Based on the electromechanical characteristics, diagnosis and monitoring of SAGE faults are carried out [9][10][11][12][13][14]. In addition, the magnetic flux and the shaft voltage are common and useful indicators to measure air-gap eccentricity.…”

Section: Introductionmentioning

confidence: 99%

Impact of Static Air-Gap Eccentricity Fault on Synchronous Generator Efficiency

He¹,

Tang²,

Sun³

et al. 2023

Energies

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This paper presents a precise analysis of the efficiency characteristic of the synchronous generator under both normal and SAGE conditions. In this work, various losses of the synchronous generator are computed by the qualitative theoretical model and the finite element analysis in detail. Further, the generator efficiency model is proposed according to the relationship between the output power and the loss. The presented model is verified in a 5-kW non-salient synchronous generator. The result demonstrates that the loss increases and the efficiency reduce as the SAGE intensifies.

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Section: Introductionmentioning

confidence: 99%

Impact of Static Air-Gap Eccentricity Fault on Synchronous Generator Efficiency

He¹,

Tang²,

Sun³

et al. 2023

Energies

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“…The main application of salient-pole synchronous machines is for hydro energy as well as smaller sized power production in industry. Typically, such generators operate uninterrupted for extended periods before they are subjected to maintenance [2]. There are three types of faults: electrical, magnetic and mechanical [3].…”

Section: Introductionmentioning

confidence: 99%

Diagnosis of Static Eccentricity in 3-Phase Synchronous Machines using a Pseudo Zero-Sequence Current

et al. 2019

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Large synchronous generators are the heart of the modern world, while producing the vast majority of the electric power consumed globally. Although they are robust devices, they are prone to degradation and failure. If such failures are not detected at an early stage, then the negative impact may be catastrophic in terms of financial costs, repair times, human lives and quality of life. This is the reason for continuous research in the field of condition monitoring aiming towards the reliable operation of synchronous generators. This paper proposes a novel technique for the diagnosis of the static eccentricity in synchronous generators. The proposed approach is off-line and non-intrusive, allowing the estimation of the fault severity with stator current measurements only. The performed work has been carried out with Finite Element Simulations and extensive experimental testing. Energies 2019, 12, 2476 2 of 16where the electrical machine operates under an asymmetrical air-gap due to displacement of the rotor. The eccentricity fault may be either static when the rotor's dislocation is fixed in space and time, or dynamic when the rotor geometric center changes continuously over time. If the two conditions co-exist, then this is known as the mixed eccentricity condition [5].The static eccentricity fault usually appears at the commissioning stages and starts as a manufacturing fault. It can be caused by improper alignment of the shaft or the stator inner ovality. Some level of inherent eccentricity is expected, however, and this is due to the very small air-gap between the rotor poles and the stator teeth [6]. The impact of the rotor weight affects the level of the static eccentricity in large electrical machines over time.The impact of eccentricity on synchronous machines has been studied in the past [6][7][8][9]. The radial and tangential forces are known to increase in the presence of eccentricity conditions [7]. It has been presented in reference [8] that variation of the air-gap magnetic reluctance will generate eddy currents in the rotor damping cage, even at unloaded operation [8]. A paper on the Unbalanced Magnetic Pull (UMP) caused by eccentricity faults in synchronous machines presented the independence between the static and dynamic eccentricity [6]. Finally, it was shown that the impact of the damper cage in case of eccentric conditions is very weak, an attribute associated with its high ohmic resistance [9]. However, the damper cage's impact on the forces due to the eccentricity fault is small, an attribute due to the cage's high ohmic resistance.Moreover, focusing on the actual diagnosis of the eccentricity fault in synchronous machines, it is clear that most past works focus on either permanent magnet [10][11][12][13] or reluctance machines [14-16], while literature is very limited for salient pole ones. Despite this unequal research effort, some contributions have been identified and are listed here. Intrusive techniques such as the installation of flux sensors to capture the air-gap magnetic flux give...

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“…Salient-pole synchronous generators are mainly used in hydroelectric plants and industrial generators driven by gas or steam turbine. In such applications, the machines must operate continuously for a long time before undergoing inspection and maintenance [2]. There are many different faults that might appear in salient-pole machines, however the major ones are the eccentricity and electrical faults [3].…”

Section: Introductionmentioning

confidence: 99%

“…However, some significant past works are referred here. Some works have focused on intrusive methods such as the monitoring of the air-gap radial flux [2], [10]. Alternatively, it has been proposed to monitor the shaft voltage during the generator operation [11]- [12].…”

Section: Introductionmentioning

confidence: 99%